#include <fstream>
#include <vector>
#include <queue>

#define vect vector< vector<int> >

using namespace std;

void read(vect &v)
{
    ifstream f("darb.in");
    int n, x, y;
    
    f >> n;
    v.resize(n+1);
    for (int i = 1; i < n; ++i)
    {
        f >> x >> y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
    
    f.close();
}

int pathLongest(vect &v, vector<int> &dist, int start)
{
    queue<int> Q;
    int node;
    
    fill(dist.begin(), dist.end(), -1);
    dist[start] = 1;
    
    Q.push(start);
    
    while (!Q.empty())
    {
        node = Q.front();
        Q.pop();
        
        for (vector<int>::const_iterator it = v[node].begin(); it != v[node].end(); ++it)
        {
            if (dist[*it] == -1)
            {
                Q.push(*it);
                dist[*it] = dist[node] + 1;
            }
        }
    }
    
    return node;
}

void solve(vect &v)
{
    ofstream f("darb.out");
    vector<int> dist(v.size());
    int node;
    
    node = pathLongest(v, dist, 1);
    node = pathLongest(v, dist, node);
    
    f << dist[node];
    f.close();
}

int main()
{
    vect v;
    read(v);
    solve(v);
    
    return 0;
}